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International audience; AbstractPurposeTo detect carnosine, anserine and homocarnosine in vivo with chemical exchange saturation transfer (CEST) at 17.2 T.MethodsCEST MR acquisitions were performed using a CEST-linescan sequence developed in-house and optimized for carnosine detection. In vivo CEST data were collected from three different regions of interest (the lower leg muscle, the olfactory bulb and the neocortex) of eight rats.ResultsThe CEST effect for carnosine, anserine and homocarnosine was characterized in phantoms, demonstrating the possibility to separate individual contributions by employing high spectral resolution (0.005 ppm) and low CEST saturation power (0.15 T). The CEST signature of these peptides was evidenced, in vivo, in the rat brain and skeletal muscle. The presence of carnosine and anserine in the muscle was corroborated by in vivo localized spectroscopy (MRS). However, the sensitivity of MRS was insufficient for carnosine and homocarnosine detection in the brain. The absolute amounts of carnosine and derivatives in the investigated tissues were determined by liquid chromatography–electrospray ionization-tandem mass spectrometry using isotopic dilution standard methods and were in agreement with the CEST results.ConclusionThe robustness of the CEST-linescan approach and the favorable conditions for CEST at ultra-high magnetic field allowed the in vivo CEST MR detection of carnosine and related peptides. This approach could be useful to investigate noninvasively the (patho)-physiological roles of these molecules.

International audience; We report the synthesis of C3-symmetric cryptophanes decorated with three aromatic amine groups on the same CTB cap and their interaction with xenon. The relative stereochemistry of these two stereoisomers syn and anti was assessed thanks to the determination of the X-ray structure of an intermediate compound. As previously observed with the tris-aza-cryptophanes analogs anti-1 and syn-2 (J. Org. Chem. 2021, 86, 11, 7648–7658), both compounds anti-5 and syn-6 show a slow in–out exchange dynamics of xenon at 11.7 T. Our work supports the idea that the presence of nitrogen atoms grafted directly onto the cryptophane backbone has a strong impact on the in–out exchange dynamics of xenon whatever their stereochemistry. This result contrasts with the case of other cryptophanes decorated solely with methoxy substituents. Finally, we demonstrate that these new derivatives can be used to design new anti/syn cryptophanes bearing suitable ligands in order to constitute potent 129Xe NMR-based sensors. An example is reported here with the synthesis of the tris-iodo derivatives anti-13 and syn-14 from compounds anti-5 and syn-6.

We report the synthesis of

Cerium (Ce) is present in high technology materials and in mineral P fertilizers and the use and discharge of such resources may change the natural status of Ce in the soil environment. Brazilian soils in farming areas are significantly exposed to increased levels of unintentionally-added Ce through intensive input of phosphate fertilizers. The aims of this study were to evaluate the ecotoxicological risk to plants growing in tropical soils contaminated with Ce, as well as to create a database to support future legislation regulating the limits of this element in Brazilian and conceivably other tropical soils. Eight crop species (corn, sorghum, rice, wheat, soybeans, sunflower, radish, and beans) were exposed to a Ce concentration gradient in two typical tropical soils (Oxisol and Inceptsol), and an artificial soil. Our findings showed that among the endpoints measured, Ce phytotoxicity was more pronounced on shoot dry matter than on percent germination and germination speed index. Sensitivity of plants is species specific and our data showed that sunflower and radish exposed to Ce were the most sensitive crop species. Soil properties such as pH, cation exchange capacity, and organic carbon may have influenced the severity of Ce phytotoxicity. Because of that, the Oxisol contaminated with this element caused higher phytotoxicity than the other soils tested. Our risk assessment results (hazardous concentration, HC5 = 281.6 mg Ce kg−1) support the idea that unintentional Ce input through P fertilizers does not pose a risk to soils of Brazilian agroecosystems.

International audience; We report the synthesis and the optical resolution of C3-symmetrical tris-azacryptophanes anti-3 and syn-4, as well as the study of their interaction with xenon via hyperpolarized 129 Xe NMR. These molecular cages are close structural analogs of the two wellknown cryptophane-A (1; chiral) and cryptophane-B (2; achiral) diastereomers since these new 2 compounds differ only by the presence of three nitrogen atoms grafted on the same cyclotribenzylene unit. The assignment of their relative (syn vs anti) and absolute configurations was made possible thanks to the combined use of quantum calculation at the DFT level and vibrational circular dichroism (VCD). More importantly, our results show that despite the large structural similarities with cryptophane-A (1) and-B (2), these two new compounds show very different behavior in the presence of xenon in organic solution. These results demonstrate that a prediction of the physical properties of the xenon@cryptophane complexes, only based on structural parameters, remains extremely difficult.

We report the synthesis and optical resolution of

Herbicide drift may cause adverse effects on natural and seminatural plant communities, and it has been debated whether the current ecological risk assessments are adequate to protect nontarget terrestrial plant species. In the present study, 9 nontarget terrestrial plant species with different lifespans (3 annual/6 perennial) belonging to 6 different plant families were exposed to 4 herbicides with different modes of action at the vegetative (6-8 leaf) and reproductive (bud) stages separately. The plant tests were conducted under controlled conditions in 2 greenhouses, 1 located in Denmark and 1 in Canada. For both growth stages, effects were recorded on vegetative (above-ground biomass 3 wk after treatment) and reproductive endpoints (number and germinability of seeds). In most cases, responses following exposure at the juvenile stage were greater than responses following exposure at the reproductive stage. For the combinations of herbicides and plant species included in the present study, we found that the sensitivities of vegetative and reproductive endpoints were equal, or else vegetative endpoints were more sensitive than reproductive endpoints. We also found that annual species were more sensitive than perennial species. The overall conclusions cover many different response patterns, and it is evident that some effects may not be found in the currently used standard tests. Generally, more pronounced effects were obtained in Denmark compared with Canada, highlighting the fact that even under standardized test conditions and following common guidelines, several uncontrollable factors can still induce variable results. Environ Toxicol Chem 2021;40:1389-1404. © 2021 SETAC.

The availability of a benchtop NMR spectrometer, of low cost and easily transportable, can allow detection of low quantities of biosensors, provided that hyperpolarized species are used. Here we show that the micromolar threshold can easily be reached, by employing laser-polarized xenon and cage-molecules reversibly hosting it. Indirect detection of caged xenon is made via chemical exchange, using ultrafast Z-spectroscopy based on spatio-temporal encoding. On this non-dedicated low-field spectrometer, several ideas are proposed to improve the signal.

International audience; Hyperpolarization techniques that can transiently boost nuclear spin polarization are generally carried out at low temperature-as in the case of dynamic nuclear polarization-or at high temperature in the gaseous state-as in the case of optically pumped noble gases. This review aims at describing the various issues and challenges that have been encountered during dissolution of hyperpolarized species, and solutions to these problems that have been or are currently proposed in the literature. During the transport of molecules from the polarizer to the NMR detection region, and when the hyperpolarized species or a precursor of hyperpolarization (e.g. parahydrogen) is introduced into the solution of interest, several obstacles need to be overcome to keep a high level of final magnetization. The choice of the magnetic field, the design of the dissolution setup, and ways to isolate hyperpolarized compounds from relaxation agents will be presented. Due to the non-equilibrium character of the hyperpolarization, new NMR pulse sequences that perform better than the classical ones will be described. Finally, three applications in the field of biology will be briefly mentioned.

The Arabidopsis seed coat contains various lipid-based (suberin and cutin), carbohydrate-based (mucilage) and phenolic-based (proanthocyanidin) polymers that may influence seed permeability to various solutes. We investigated the roles of these polymers in protection against a potential soil contaminant, chromium (Cr3+), during seed germination in Arabidopsis thaliana. Wild-type and mutants impaired in one or more of these seed coat polymers were exposed to different Cr3+ concentrations (0, 50, 100, 200, 400 and 800 mg L−1) during seed stratification and early imbibition. Mutants with significant reductions in seed coat suberin were highly sensitive to Cr3+. Suberin-altered mutants demonstrated reduced seed germination with increasing Cr3+ concentrations. At the highest level of Cr3+ (800 mg L−1), mutants deficient in suberin showed reduced embryo viability, indicating that chromium was directly damaging the embryo. This was correlated with increased seed coat permeability of the suberin-deficient mutants to tetrazolium salts. A cutin mutant that is reduced in seed coat C16-C18 α,ω-dicarboxylic fatty acids of the polyester was not affected by Cr3+. Mutants that were strongly reduced in rhamnose, a component of rhamnogalacturonan-I (RG-I), had moderate sensitivity to Cr3+ in terms of seed germination rates. Although many proanthocyanidin mutants displayed reduced seed germination in the presence of Cr3+, the viabilities of their embryos were only slightly reduced at high Cr3+ concentrations. We speculate that Cr3+ exposure induced germination arrest in proanthocyanidin mutants, which have a defective endosperm-associated cuticle. Our findings provide evidence that various polymer types in Arabidopsis seed coat provide protection against Cr3+ by different mechanisms and degrees. Seed coat suberin was identified as the main physical barrier against Cr3+ toxicity. The results also highlight the risks associated with Cr3+ toxicity on the persistence of seeds that have relatively low seed coat suberin in soils contaminated with high levels of chromium.

Questions Do agricultural land use and nitrogen enrichment have negative effects on riparian soil seed banks? What is the potential of the soil seed bank for the conservation and restoration of native riparian plant diversity? Are non-native dominant grass species affected by agriculture and do they affect species richness? Location South Nation River watershed (an agricultural watershed), Ontario, Canada. Methods We examined the riparian aboveground vegetation at 24 sites located across a large (~4000 km2) North American watershed and identified the corresponding soil seed bank composition from soil cores using the seedling emergence method. The aboveground vegetation and soil seed bank species compositions were compared in terms of species richness, percentage of non-native species and a floristic quality index. Factors affecting these descriptors of plants communities (concentration of in-stream nitrate and the percentages of surrounding natural habitat and annual crop land) were assessed. The effects of agriculture on two dominant non-native grasses species and their effects on species richness were also assessed. Results In total, 274 plant taxa were identified, including 181 taxa in the soil seed bank and 231 taxa in the vegetation. Overall species richness was high in both the soil seed bank and aboveground vegetation and was unaffected by measures of agricultural intensity (surrounding annual crop land and nitrogen enrichment). Aboveground vegetation species richness was strongly negatively affected by the widespread and dominant non-native grasses, Phalaris arundinacea and Bromus inermis, whereas soil seed bank species richness was unaffected. The community compositions of both the soil seed bank and vegetation were negatively affected by the loss of natural habitat and by nitrogen enrichment. In fact, an increase in the percentage of non-native species and a decrease in floristic quality were observed along a gradient of agricultural intensity. Conclusions Species richness of the soil seed bank demonstrated resilience to invasions by P. arundinacea and B. inermis and the soil seed bank showed good potential for conservation of taxonomic diversity. However, the loss of natural habitat and nitrogen enrichment had negative effects on the soil seed bank community composition that may lead to an eventual decline in aboveground species richness. This article is protected by copyright. All rights reserved.

Questions Plant community resilience largely depends on the secondary succession induced by species re-colonization from seed banks. Soil seed bank resilience is, however, poorly understood, especially in regularly disturbed habitats like riparian zones. Two questions were asked: what are the changes in species diversity experienced by riparian soil seed banks along successional trajectories, and to what extent do riparian soil seed banks promote vegetation resilience during secondary succession? Location Southeastern Quebec, Canada. Methods Soils were collected along five rivers in field edges and riverbanks of post-agricultural riparian zones with three contrasting successional stages (unplanted – planted with trees 15-17 years prior to sampling – natural riparian forests), and their seed bank composition determined with the seedling emergence method. Species richness in seed banks was assessed along successional trajectories for distinct ecological groups, using linear mixed models. The compositions of soil seed banks and standing vegetation (from botanical surveys) were compared based on NMDS and Indicator Species Analysis. Results Seed bank species richness decreased along successional trajectories. Tree-planted riparian zones were generally closer to unplanted riparian zones than to natural riparian forests, the latter being more species-rich for natives, trees, shrubs and zoochores, and species-poor for exotics, forbs and stress-tolerators. Likewise, seed bank species composition of unplanted and tree-planted riparian zones was similar but differed from those of natural riparian forests. Conversely, standing vegetation of tree-planted riparian zones was intermediate between early- and late-successional stages, at least at field edges. For the three successional stages, seed bank composition clearly differed from standing vegetation. Conclusions The high resilience of riparian plant communities appeared poorly related to the dynamics of their soil seed banks. This species shift between seed banks and standing vegetation during secondary succession is likely due to periodic flooding leading to the regular turnover of seeds. The resilience of riparian communities might thus be more influenced by spatial dispersal along rivers and across landscapes than by in situ temporal dispersal in soils. This article is protected by copyright. All rights reserved.

Oil sands mining in Alberta, Canada, has been steadily increasing over the last 50 years. The extent to which the surrounding vegetation has been altered/contaminated by pollutants released during bitumen extraction has not been a focus of oil sands environmental monitoring efforts. The objectives of this study were to assess plant species richness and composition in wetlands and uplands in the vicinity of oil sands mining areas and to measure levels of contamination of trace metals and polycyclic aromatic hydrocarbons (PAHs) in soils and plants. Twenty-two sites were selected in three locations: near to (OS, n = 7), West (n = 7), and East (n = 8) of oil sands mining operations. Aboveground plant species were inventoried and soil was collected for a seedbank study. Soils and plants were collected for analyses of 28 metals and 40 parent and alkylated PAHs. Plant species richness and composition differed significantly among locations. More species were found in the OS sites, many of them being non-native, than in East and West sites, which contained almost exclusively native perennials. PAH levels were significantly higher in OS sites, and were mostly comprised of alkylated PAHs. Patterns of PAH distribution indicated contamination from bitumen/petroleum in four sites; other combustion types may have affected five additional sites at different levels. Metals were also elevated in OS sites. Metal levels were significantly correlated with distance to upgrader facilities. Ratios of some metals in soil vs. above- and belowground plant parts were significantly higher in West and East than in OS sites, likely due in part to pH as soil was acidic at the East and West locations but alkaline at OS sites. This study showed that sites located near oil sands mining operations were contaminated with PAHs and metals, and that the vegetation composition at these sites greatly differed from less disturbed areas.

Herbicides have been shown to reduce flower production and to delay flowering, with results varying among herbicides and tested plant species. We investigated the effects of herbicides on flowering in an extensive greenhouse study conducted in Canada and Denmark. The effects of low doses of 5 different herbicides (bromoxynil, ioxynil + bromoxynil, metsulfuron-methyl, clopyralid, and glyphosate), simulating realistic drift scenarios (1 and 5% recommended field rates), on plant flowering were examined using 9 wild plant species exposed at either the seedling (6- to 8-leaf) or flower bud stage. Following herbicide exposure, initial flowering date as well as flower production over time were recorded over the growing period. The effect of herbicides on cumulative flower numbers and flowering time were modeled using Gompertz growth models. Significant delays to peak flowering and/or reductions in flower production were observed in at least one plant species for all tested herbicides, with glyphosate often exhibiting the greatest negative effects, that is, plant death. Except for ioxynil + bromoxynil, there was no clear evidence of either the seedling or the flower bud stage being more sensitive. Overall, 58% of all species × life stage × herbicide treatments resulted in either a statistically significant or a strong decline in flower production with herbicide application rates up to 5% of recommended field rates, whereas significant or strong delays in peak flowering were also detected but were slightly less common. Effects at 1% label rates were minimal. Simultaneous delays to peak flowering and reductions in total flower production occurred in approximately 25% of all cases, indicating that herbicide application rates simulating realistic drift scenarios would likely have negative effects on wild floral communities. Environ Toxicol Chem 2020;39:1244-1256. © 2020 SETAC.

Plant competitive interactions influence the effect of herbicides, and the effect of competitive interactions on plant responses may be important to include in the ecological risk assessment of herbicides. In the present study the effect of competitive interactions and sublethal doses of 2 herbicides on plant species was investigated in competition experiments and fitted to empirical competition models. Two nontarget species commonly found in agroecosystems (Centaurea cyanus L. and Silene noctiflora L.) and 2 herbicides (glyphosate and metsulfuron methyl) were used in separate experiments. Plants were sprayed at the 6- to 8-leaf stage. Effects of herbicide treatments and plant density were modeled by generalization of a discrete hyperbolic competition model. The 10% effective dose (ED10) was calculated for C. cyanus. All experiments showed that as density increased, plants were negatively affected. Furthermore, in all cases, C. cyanus remained a better competitor than S. noctiflora. Nevertheless, the density of S. noctiflora (competitor) was an influential element in determining the ED10 of C. cyanus measured at the mature stage. With herbicide exposure, the competitive interactions were further altered; C. cyanus was less affected by glyphosate when S. noctiflora increased to high density. In contrast, at the young stage, conspecific density was important in determining the sensitivity of C. cyanus to metsulfuron methyl, whereas the density of the competitor S. noctiflora had a limited influence. Overall, the results demonstrate the importance of integrating the effect of herbicide and species interactions measured at the reproductive stage into the ecological risk assessments of pesticides. Environ Toxicol Chem 2019;00:1-12. (c) 2019 SETAC

International audience; In this article, we present the synthesis of new cryptophane-type hosts capable of binding xenon in aqueous media and that may be useful for the development of xenon-based magnetic resonance imaging derivatives. The synthetic route proposed was chosen to facilitate both the introduction of water-solubilizing substituents and the functionalization of the host with a single arm showing recognition properties that constitute two crucial steps. This was made possible by preparing new cryptophane-223 derivatives bearing two different chemical functions that can be easily modified at a later stage. Thus, subsequent reactions allowed the design of a new cryptophane host able to bind zinc or nickel cations. The ability of this molecule to bind cationic species was assessed by calorimetric titration experiments and hyperpolarized 129Xe NMR. The advantages and disadvantages of this approach are discussed.

A full understanding of biological phenomena involves sensitive and noninvasive detection. Herein, we report the optimization of a probe for intracellular proteins that combines the advantages of fluorescence and hyperpolarized 129 Xe NMR spectroscopy detection. The fluorescence detection part is composed of six residues containing a tetracysteine tag (-CCXXCC-) genetically incorporated into the protein of interest and of a small organic molecule, CrAsH. CrAsH becomes fluorescent if it binds to the tetracysteine tag. The part of the biosensor that enables detection by means of 129 Xe NMR spectroscopy, which is linked to the CrAsH moiety by a spacer, is based on a cryptophane core that is fully suited to reversibly host xenon. Three different peptides, containing the tetracysteine tag and four organic biosensors of different stereochemistry, are benchmarked to propose the best couple that is fully suited for the in vitro detection of proteins.

A full understanding of biological phenomena involves sensitive and noninvasive detection. Herein, we report the optimization of a probe for intracellular proteins that combines the advantages of fluorescence and hyperpolarized

Agrochemicals, including fertilizers and herbicides, are significant contributors of non-point source pollution to surface waters and have the potential to negatively affect periphyton. We characterized periphyton communities using pigment markers to assess the effects of nutrient enrichment and the herbicide atrazine with in situ experimental manipulations and by examining changes in community structure along existing agrochemical gradients. In 2008, the addition of nutrients (20mg/L nitrate and 1.25mg/L reactive phosphate), atrazine (20μg/L) and a combination of both nutrients and atrazine had no significant effect on periphyton biomass or community structure in a stream periphytometer experiment. In 2009, similar experiments with higher concentrations of atrazine (200μg/L) at two stream sites led to some minor effects. In contrast, at the watershed scale (2010) periphyton biomass (mg/m2 chlorophyll a) increased significantly along correlated gradients of nitrate and atrazine but no direct effects of reactive phosphate were observed. Across the watershed, the average periphyton community was composed of Bacillariophyceae (60.9%), Chlorophyceae (28.1%), Cryptophyceae (6.9%) and Euglenophyceae (4.1%), with the Bacillariophyceae associated with high turbidity and the Chlorophyceae with nitrate enrichment. Overall, effects of nitrate on periphyton biomass and community structure superseded effects of reactive phosphate and atrazine.

Summary In agricultural catchments, streams are intimately connected with croplands and are exposed to agrochemicals such as fertilisers and herbicides. In North American streams, the effects of nutrient enrichment on riparian and aquatic plant community structure are not well established and the effects of herbicides are largely unknown. We identified the riparian and aquatic plant community at 12 paired stream/river sites (24 in total, Strahler stream order 3–6) located across a large North American agricultural catchment. Field sites ranged in surrounding agricultural land use (2.7–100% annual crops) and in-stream June concentrations of reactive phosphate (6–65 μg L−1 as phosphorus) and nitrate (3–3981 μg L−1 as nitrogen). Atrazine, a herbicide commonly used on corn crops in North America, was widespread throughout the catchment with time-weighted-average concentrations ranging from 4 to 412 ng L−1 over a 56-day period. Atrazine concentrations were >100 ng L−1 at over half the field sites. In total, 285 riparian and aquatic plant taxa were identified. Effects of agrochemicals on descriptors of plant communities were assessed by comparing paired sites surrounded by low or high levels of agriculture and examining changes across the catchment. Agrochemicals had no effect on overall species richness. However, the percentage of non-native species increased across the catchment along a gradient of increasing nitrate. A decline in submerged macrophytes was associated with enrichment of both nitrate and reactive phosphate, whereas no direct effects of atrazine were observed. A floristic quality assessment was used to determine further effects of agrochemicals on riparian and aquatic plant communities. A ranking system, based on native status and tolerance to disturbance, was used to assign coefficient of conservation values to each species. Floristic quality was subsequently calculated as a function of species richness and the average coefficient of conservation value at each site. Overall floristic quality decreased as nitrate increased. Species positively associated with nitrate were typically fast-growing, weedy, riparian species, whereas species negatively associated with nitrate were characteristic of less disturbed areas and represented a range of growth forms. We conclude that nutrient enrichment, especially of nitrate, has multiple negative effects on riparian and aquatic plant communities that override effects of the herbicide atrazine. Our results highlight the need to reduce inputs of agrochemicals to streams and to regulate nitrogen in addition to phosphorus.

The discovery of hybridization between the invasive Eurasian watermilfoil (Myriophyllum spicatum L.) and native northern watermilfoil (Myriophyllum sibiricum Kom.) has generated interest in establishing the hybrid’s distribution and invasiveness. Identification of hybrid M. spicatum × M. sibiricum requires molecular genetic analysis, however, as the hybrid’s morphology overlaps with both parent species. Using plants collected from 10 lakes in Ontario, Canada, we compared a previous method of identification (sequencing the nuclear ITS region) with a simpler screening method (PCR-RFLP of the ITS region). Both methods agreed on the identification of hybrid M. spicatum × M. sibiricum and both parent species, supporting the suitability of PCR-RFLP to screen for the hybrid. Four of 29 samples were identified as hybrid M. spicatum × M. sibiricum, which were all found in three adjacent lakes associated with the Rideau Canal Waterway. The PCR-RFLP method should enable greater sampling effort to screen for hybrid M. spicatum × M. sibiricum and establish its geographic distribution across connected waterways.

International audience; Although Non-Small Cell Lung Cancer (NSCLC) is one of the main causes of cancer death, very little improvement has been made in the last decades regarding diagnosis and outcomes. In this study, a bimodal fluorescence/$^{129}$Xe NMR probe containing a xenon host, a fluorescent moiety and a therapeutic antibody has been designed to target the Epidermal Growth Factor Receptors (EGFR) overexpressed in cancer cells. This biosensor shows high selectivity for the EGFR, and a biological activity similar to that of the antibody. It is detected with high specificity and high sensitivity (sub-nanomolar range) through hyperpolarized $^{129}$Xe NMR. This promising system should find important applications for theranostic use.

Although Non-Small Cell Lung Cancer (NSCLC) is one of the main causes of cancer death, very little improvement has been made in the last decades regarding diagnosis and outcomes. In this study, a bimodal fluorescence/

International audience; We report the laser-polarized 129 Xe and 1 H NMR spectra of a series of cryptophane derivatives that differ only by the number of methoxy groups attached on their benzene rings and the arrangement syn or anti of the linkers (compounds 6a-s, 9a-s, 12a-s). All these compounds bind xenon even though the characteristic signal of the gas encapsulated in the cavity of the cage-molecule cannot be always detected. Interestingly, the exchange dynamics of xenon strongly depends on the degree of substitution and is different from that of the cryptophane derivatives studied previously. In solution, the 1 H NMR spectra of these derivatives show the presence of different conformations in a slow exchange regime that can be explained by a decrease of the flexibility of their skeleton. Thanks to 129 Xe-1 H dipolar cross-relaxation (SPINOE) spectra we demonstrate that a single conformation present in solution can bind xenon.

We report the laser-polarized

International audience; Gaining an understanding of the nature of host–guest interactions in supramolecular complexes involving heavy atoms is a difficult task. Described herein is a robust simulation method applied to complexes between xenon and members of a cryptophane family. The calculated chemical shift of xenon caged in a H2O2 probe, as modeled by quantum chemistry with complementary-orbital, topological, and energy-decomposition analyses, is in excellent agreement with that observed in hyperpolarized 129Xe NMR spectra. This approach can be extended to other van der Waals complexes involving heavy atoms.

Polar organic chemical integrative samplers (POCIS) were used to estimate atrazine contamination at 24 stream/river sites located across a watershed with land use ranging from 6.7 to 97.4% annual crops and surface water nitrate concentrations ranging from 3 to 5404 μg/L. A gradient of atrazine contamination spanning two orders of magnitude was observed over two POCIS deployments of 28 d and was positively correlated with measures of agricultural intensity. The metabolite desisopropyl atrazine was used as a performance reference compound in field calibration studies. Sampling rates were similar between field sites but differed seasonally. Temperature had a significant effect on sampling rates while other environmental variables, including water velocity, appeared to have no effect on sampling rates. A performance reference compound approach showed potential in evaluating spatial and temporal differences in field sampling rates and as a tool for further understanding processes governing uptake of polar compounds by POCIS.

The phytotoxicity of rare earth elements (REEs) is still poorly understood. The exposure–response relationships of three native Canadian plant species (common milkweed, Asclepias syriaca L., showy ticktrefoil, Desmodium canadense (L.) DC. and switchgrass, Panicum virgatum L.) and two commonly used crop species (radish, Raphanus sativus L., and tomato, Solanum lycopersicum L.) to the REEs lanthanum (La), yttrium (Y) and cerium (Ce) were tested. In separate experiments, seven to eight doses of each element were added to the soil prior to sowing seeds. Effects of REE dose on germination were established through measures of total percent germination and speed of germination; effects on growth were established through determination of above ground biomass. Ce was also tested at two pH levels and plant tissue analysis was conducted on pooled samples. Effects on germination were mostly observed with Ce at low pH. However, effects on growth were more pronounced, with detectable inhibition concentrations causing 10% and 25% reductions in biomass for the two native forb species (A. syriaca and D. canadense) with all REEs and on all species tested with Ce in both soil pH treatments. Concentration of Ce in aboveground biomass was lower than root Ce content, and followed the dose–response trend. From values measured in natural soils around the world, our results continue to support the notion that REEs are of limited toxicity and not considered extremely hazardous to the environment. However, in areas where REE contamination is likely, the slow accumulation of these elements in the environment could become problematic.

We describe the synthesis of a highly water-soluble cryptophane 1 that can be seen as a universal platform for the construction of (129)Xe magnetic resonance imaging (MRI)-based biosensors. Compound 1 is easily functionalized by Huisgen cycloaddition and exhibits excellent xenon-encapsulation properties. In addition, 1 is nontoxic at the concentrations typically used for hyperpolarized (129)Xe MRI.

Elevated chromium levels in soil from mining can impact the environment, including plants. Mining of chromium is concentrated in South Africa, several Asian countries, and potentially in Northern Ontario, Canada, raising concerns since chromium toxicity to wild plants is poorly understood. In the first experiment, concentration-response tests were conducted to evaluate effects of chromium on terrestrial and wetland plants. Following established guidelines using artificial soil, seeds of 32 species were exposed to chromium (Cr 3+ ) at concentrations simulating contamination (0–1000 mg kg −1 ). This study found that low levels of chromium (250 mg kg −1 ) adversely affected the germination of 22% of species (33% of all families), while higher levels (500 and 1000 mg kg −1 ) affected 69% and 94% of species, respectively, from 89% of the families. Secondly, effects on seedbanks were studied using soil collected in Northern Ontario and exposed to Cr 3+ at equivalent concentrations (0–1000 mg kg −1 ). Effects were less severe in the seedbank study with significant differences only observed at 1000 mg kg −1 . Seeds exposed to Cr 3+ during stratification were greatly affected. Seed size was a contributing factor as was possibly the seed coat barrier. This study represents an initial step in understanding Cr 3+ toxicity on wild plants and could form the basis for future risk assessments.

The advent of spin-hyperpolarization techniques designed to overcome the sensitivity issue of nuclear magnetic resonance owing to polarization transfer from more ordered systems has recently raised great enthusiasm. However, the out-of-equilibrium character of the polarization requires a close proximity between the area of production and the site of use. We present here a mobile spin-exchange optical pumping setup that enables production of laser-polarized noble gases in a standalone mode, in close proximity to hospitals or research laboratories. Only compressed air and mains power need to be supplied by the host laboratory.

Land-use change and intensification threaten bee populations worldwide, imperilling pollination services. Global models are needed to better characterise, project, and mitigate bees' responses to these human impacts. The available data are, however, geographically and taxonomically unrepresentative; most data are from North America and Western Europe, overrepresenting bumblebees and raising concerns that model results may not be generalizable to other regions and taxa. To assess whether the geographic and taxonomic biases of data could undermine effectiveness of models for conservation policy, we have collated from the published literature a global dataset of bee diversity at sites facing land-use change and intensification, and assess whether bee responses to these pressures vary across 11 regions (Western, Northern, Eastern and Southern Europe; North, Central and South America; Australia and New Zealand; South East Asia; Middle and Southern Africa) and between bumblebees and other bees. Our analyses highlight strong regionally-based responses of total abundance, species richness and Simpson's diversity to land use, caused by variation in the sensitivity of species and potentially in the nature of threats. These results suggest that global extrapolation of models based on geographically and taxonomically restricted data may underestimate the true uncertainty, increasing the risk of ecological surprises. Fil: De Palma, Adriana. Natural History Museum; Reino Unido. Imperial College London; Reino Unido Fil: Abrahamczyk, Stefan. Universitat Bonn; Alemania Fil: Aizen, Marcelo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Albrecht, Matthias. Institute for Sustainability Sciences; Suiza Fil: Basset, Yves. Smithsonian Tropical Research Institute; Panamá Fil: Bates, Adam. Nottingham Trent University; Reino Unido Fil: Blake, Robin J.. University of Reading; Reino Unido Fil: Boutin, Céline. Carleton University; Canadá Fil: Bugter, Rob. Wageningen University and Research; Países Bajos Fil: Connop, Stuart. University of East London; Reino Unido Fil: Cruz López, Leopoldo. El Colegio de la Frontera del Sur; México Fil: Cunningham, Saul A.. CSIRO Exploration and Mining; Australia Fil: Darvill, Ben. University of Stirling; Reino Unido Fil: Diekötter, Tim. Geomar-Helmholtz Centre for Ocean Research Kiel; Alemania. University Marburg; Alemania. Institute of Integrative Biology; Suiza Fil: Dorn, Silvia. ETH Zurich; Suiza Fil: Downing, Nicola. Royal Society for the Protection of Birds; Reino Unido Fil: Entling, Martin H.. Universitat Koblenz; Alemania Fil: Farwig, Nina. Universitat Phillips; Alemania Fil: Felicioli, Antonio. Università degli Studi di Pisa; Italia Fil: Fonte, Steven J.. State University of Colorado - Fort Collins; Estados Unidos Fil: Fowler, Robert. University of Sussex; Reino Unido Fil: Franzén, Markus. Helmholtz Centre for Environmental Research; Alemania Fil: Goulson, Dave. Universität Göttingen; Alemania Fil: Grass, Ingo. Universität Göttingen; Alemania Fil: Hanley, Mick E.. University of Iowa; Estados Unidos Fil: Hendrix, Stephen D.. University of Iowa; Estados Unidos Fil: Herrmann, Farina. Universität Würzburg; Alemania Fil: Herzog, Felix. Institut for Sustainability Sciences; Suiza Fil: Holzschuh, Andrea. Universität Würzburg; Alemania Fil: Jauker, Birgit. Justus-Liebig University; Alemania Fil: Kessler, Michael. Institut für Systematische und Evolutionäre Botanik; Suiza Fil: Knight, M.E.. Plymouth University; Reino Unido Fil: Kruess, Andreas. Federal Agency for Nature Conservation; Alemania Fil: Lavelle, Patrick. Centre National de la Recherche Scientifique. Institut de Recherche pour le Développement; Francia. Centro Internacional de Agricultura Tropical; Colombia Fil: Le Féon, Violette Alice Marie. Institut National de la Recherche Agronomique; Francia Fil: Lentini, Pia. University of Melbourne; Australia Fil: Malone, Louise A.. New Zealand Institute for Plant and Food Research Ltd; Nueva Zelanda Fil: Marshall, Jon. Marshall Agroecology Ltd; Reino Unido Fil: Pachón, Eliana Martínez. Universidad Nacional de Colombia; Colombia Fil: McFrederick, Quinn S.. University of California; Estados Unidos Fil: Morales, Carolina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Mudri Stojnic, Sonja. University of Novi Sad; Serbia Fil: Nates Parra, Guiomar. Universidad Nacional de Colombia; Colombia Fil: Nilsson, Sven G.. Lund University; Suecia Fil: Öckinger, Erik. Swedish University of Agricultural Sciences; Suecia Fil: Osgathorpe, Lynne. RSPB; Reino Unido Fil: Parra-H, Alejandro. Universidad Nacional de Colombia; Colombia. Corporación para la Gestión de Servicios Ecosistémicos, Polinización y Abejas; Colombia Fil: Peres, Carlos A.. University of East Anglia; Reino Unido Fil: Persson, Anna S.. Lund University; Suecia Fil: Petanidou, Theodora. University of the Aegean; Grecia Fil: Poveda, Katja. Cornell University; Estados Unidos Fil: Power, Eileen F.. Trinity College Dublin; Irlanda Fil: Quaranta, Marino. Consiglio per la Ricerca in Agricoltura e l'Analisi del l'Economía Agraria; Italia Fil: Quintero, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina Fil: Rader, Romina. University of New England; Australia Fil: Richards, Miriam H.. Brock University; Canadá Fil: Roulston, Tai. University of Virginia; Estados Unidos Fil: Rousseau, Laurent. Université du Québec a Montreal; Canadá Fil: Sadler, Jonathan P.. University of Birmingham; Reino Unido Fil: Samnegård, Ulrika. University of Birmingham; Reino Unido Fil: Schellhorn, Nancy A.. CSIRO Exploration and Mining; Australia Fil: Schüepp, Christof. University of Bern; Suiza Fil: Schweiger, Oliver. Helmholtz Centre for Environmental Research; Alemania Fil: Smith Pardo, Allan H.. United States Department of Agriculture; Estados Unidos. Universidad Nacional de Colombia; Colombia Fil: Steffan Dewenter, Ingolf. Universität Würzburg; Alemania Fil: Stout, Jane C.. Trinity College Dublin; Irlanda Fil: Tonietto, Rebecca K.. Northwestern University; Estados Unidos. Chicago Botanic Garden; Estados Unidos Fil: Teja, Tscharntke. Universität Göttingen; Alemania Fil: Tylianakis, Jason M.. Imperial College London; Reino Unido. University of Canterbury; Nueva Zelanda Fil: Verboven, Hans A. F.. Katholikie Universiteit Leuven; Bélgica Fil: Vergara, Carlos H.. Benemérita Universidad Autónoma de Puebla; México Fil: Verhulst, Jort. No especifíca; Fil: Westphal, Catrin. Universität Göttingen; Alemania Fil: Yoon, Hyung Joo. National Institute of Agricultural Science; Corea del Sur Fil: Purvis, Andy. Natural History Museum; Reino Unido. Imperial College London; Reino Unido

International audience; Background: Few studies have focused on the social inequalities associated with environmental noise despite its significant potential health effects. This study analysed the associations between area socioeconomic status (SES) and potential residential exposure to road traffic noise at a small-area level in Marseilles, second largest city in France. Methods: We calculated two potential road noise exposure indicators (PNEI) at the census block level (for 24-h and night periods), with the noise propagation prediction model CadnaA. We built a deprivation index from census data to estimate SES at the census block level. Locally estimated scatterplot smoothing diagrams described the associations between this index and PNEIs. Since the extent to which coefficient values vary between standard regression models and spatial methods are sensitive to the specific spatial model, we analysed these associations further with various regression models controlling for spatial autocorrelation and conducted sensitivity analyses with different spatial weight matrices. Results: We observed a non-linear relation between the PNEIs and the deprivation index: exposure levels were highest in the intermediate categories. All the spatial models led to a better fit and more or less pronounced reductions of the regression coefficients; the shape of the relations nonetheless remained the same. Conclusion: Finding the highest noise exposure in midlevel deprivation areas was unexpected, given the general literature on environmental inequalities. It highlights the need to study the diversity of the patterns of environmental inequalities across various economic, social and cultural contexts. Comparative studies of environmental inequalities are needed, between regions and countries, for noise and other pollutants.

International audience; Xenon capsule: A smart 129Xe NMR-based sensor of Zn2+ ions for magnetic resonance imaging (MRI) is proposed. The resonance frequency of xenon encapsulated in a cryptophane that bears a nitrilotriacetic ligand moiety varies when Zn2+ ions are present in solution (see picture). With hyper-polarized gas, such a construct enables detection of 100 nM zinc in one xenon batch, a threshold 300 times lower than achieved with gadolinium chelates.

Habitat destruction and degradation are important drivers of biodiversity loss within agro-ecosystems. However, little is known about the effect of farming practices and the value of woody hedgerows on Lepidoptera in North America. The purpose of this work was to study moth diversity in woody hedgerows and croplands of organic and conventional farms. In addition, the influence of vegetation composition and abiotic variables on species richness, abundance, and composition was examined. Moths were sampled with light traps during six weeks in the summer of 2001. Vegetation data and abiotic variables were obtained for all sites. In total, 26,020 individuals from 12 families and 408 species were captured. Most species were uncommon. Only 35 species included100 individuals while for 71% of species10 individuals were found. The Noctuidae represented 221 species and 85% of all individuals captured. Woody hedgerows harbored more species and in greater number than croplands. There was no significant difference in moth diversity between organic and conventional farms, except that the Notodontidae were significantly more species rich in organic than in conventional sites. Results show that species richness, abundance, and composition were greatly influenced by habitat types (hedgerow versus crop field) and abiotic variables (minimum temperature which was correlated to moon illumination, rainfall, and cloud cover). Moth species composition was significantly correlated to vegetation composition. This study broadens our understanding of the factors driving moth diversity and expands our knowledge of their geographic range. The maintenance of noncrop habitats such as woody hedgerows within agro-ecosystems seems paramount to preserving the biodiversity and abundance of many organisms, including moths.

The aim of this study was to evaluate the effect of farming management (field and boundary management), boundary structure (width and habitat assemblage), and landscape heterogeneity on plant species composition in field boundaries. Plant species were characterised according to their conservation value, life form and affinity to soil nutrient conditions. We surveyed 30 field boundaries next to organic fields and 30 next to conventional fields distributed along a gradient of landscape complexity. A Detrended Correspondence Analysis was performed using all 517 species recorded in order to study the variation in species composition. Field and boundary management, boundary width, habitat assemblage of field boundaries (estimated with the percentage cover of Mediterranean grasslands) and landscape heterogeneity contributed significantly in predicting the variation in species composition. Perennial species of conservation value with affinity to nutrient-poor soil conditions were more likely to be found in wide managed boundaries characterized by a high percentage cover of Mediterranean grasslands, which are adjacent to organic fields and within heterogeneous landscapes.

We show that the differentiation between internal and external compartments of various biological cells in suspension can be made via simple NMR spectra of hyperpolarized 129Xe. The spectral separation between the signals of 129Xe in these two compartments is already known for red blood cells, because of the strong interaction of the noble gas with hemoglobin. The observation of two separate peaks in the 200-ppm region can be seen with both eukaryotic and prokaryotic cells, some of which are not known to contain paramagnetic proteins in large quantities. Using different experiments in which the cells are lysed, swell or are blocked in G2 phase, we demonstrate that the low-field-shifted peak observed corresponds to xenon in the aqueous pool inside the cells and not in the membranes. The presence of this additional peak is a clear indication of cell integrity, and its integration allows the quantification of the total cell volume. The relaxation time of intracellular xenon is sufficiently long to open up promising perspectives for cell characterization. The exchange time between the inner and outer cell compartments (on the order of 30 ms) renders possible the targeting of intracellular receptors, whereas the observation of chemical shift variations represents a method of revealing the presence of toxic species in the cells. Copyright © 2011 John Wiley & Sons, Ltd.

The unique plant community on Middle Island, Lake Erie, Canada, has been greatly modified by double-crested cormorants (Phalacrocorax auritus Less.) whose population has increased enormously in the last two decades. The aims of this study were to assess the impact of cormorants on island tree canopy, understorey vegetation, soil seedbank, and soil chemistry. The ultimate objective was to assess the resilience of the vegetation community for recovery should cormorant nest densities decrease significantly. Forty-three point stations were established in a grid system covering the entire island. The herbaceous and woody vegetation was surveyed over 2 years and tree crown damage was assessed at each point station. In 2008, soil samples were collected for both chemical analysis and a seedbank inventory. Vegetation and seedbank species richness were impoverished compared to the vegetation surveyed prior to cormorant colonization. Cormorants affected not only the tree canopy where they nested but also the understorey vegetation. Exotic plant species were very common in the standing vegetation and constituted the bulk of the abundance in the seedbank. However, there was little relationship between aboveground vegetation and seedbank composition. Cormorants appeared to have little influence on seedbank richness, abundance, and composition. Notably, several species of conservation interest were found in the aboveground vegetation and in the seedbank providing a positive sign for future efforts to restore island plant communities.

Changes in farming practices over the second half of the twentieth century greatly reduced the extent of natural areas remaining within agricultural landscapes. Field margins and hedgerows have recently been recognized as important habitat in maintaining wildlife diversity and proper ecosystem functioning. Ecotones, defined as the transitionary area of vegetation between woody plant species and the arable crop, are an especially important landscape element for birds and arthropods. In this manuscript, we aimed to evaluate which hedgerow attribute was best at predicting avian densities in a conventional and organic farming landscape. Furthermore, we wished to investigate if these same hedgerow attributes could explain arthropod family density, richness and diversity, and how these were correlated to avian densities. An information theory-based multimodel inference method was used to identify which factors influenced variability in avian densities. Although not always significant, avian densities increased with arthropod richness at our study sites. Ecotone width is the best predictor of avian densities and arthropod richness while percent gap is the most important factor if a manager wishes to increase avian diversity (H’) in hedgerow habitats. Increasing ecotone width benefits both avian densities and arthropod richness that in turn further increases bird numbers in our farming landscape.

Intensification of agriculture and the corresponding increase in herbicide use has led to concern regarding the effects these chemicals may have on nontarget plants of agroecosystems. Current pesticide registration guidelines are focused on testing crop species grown singly in pots under greenhouse conditions and may not provide adequate measures of protection to noncrop species. The objective of the present study was to compare the response of terrestrial and wetland plants to the herbicides glyphosate and atrazine when grown singly in pots versus under different microcosm conditions. Greenhouse microcosms were generally more sensitive than single-species tests. Plants grown for an extended test period or in seminatural field conditions were generally less sensitive to herbicides. Sensitivity was found to be dependent on interactions between species and test conditions. Changes in community structure were observed in herbicide-treated microcosms that would not be predicted from single-species testing. Single-species tests are useful because they are inexpensive, can demonstrate clear dose-response patterns uncomplicated by other factors influencing growth, and are able to provide a measure of the sensitivity of a given species to glyphosate and atrazine. However, they are unable to predict subtle changes in community structure that may have important long-term consequences.

Arthropods were inventoried in crop fields and adjacent woody hedgerows of organic and conventional farms situated in south-central Ontario, Canada. The objective was to assess the total abundance, family richness, and composition of beneficial and phytophagous arthropods in the 2 farming systems and to examine the contributions of the vegetation present and landscape features on arthropod abundance and composition. Two hundred and forty sticky traps were installed (24 sites) and 170 sweep net collections were conducted (17 sites) in crop fields and adjacent woody hedgerows of organic and conventional sites. A total of 30 807 individual arthropods belonging to 131 families were recorded during the study. No spatial autocorrelation was detected among the arthropod samples. The study showed that beneficial and phytophagous arthropod abundance differed between organic and conventional sites (only with sweep net) but family richness did not. Beneficial arthropods were more abundant in woody hedgerow...

Many areas in north-eastern North America were historically cleared for agriculture and subsequently abandoned. The resulting woodlots are exposed to varying degrees of recent disturbance. This paper examines the contributions of land use history and recent disturbance on the species richness and community composition of wooded areas in an agricultural landscape. Woodlots were categorized according to land clearance history, past grazing, and recent disturbance, such as the presence of roads or selective cutting. Vegetation surveys resulted in the identification of 250 herbaceous plant species, 44 of which were classified as exotic. While no influence of recent disturbance on community composition was detected, past land use influenced species richness for all plant groups examined. General linear models indicated that herbaceous, native, and forest species richness was highest in historically partially cleared sites; while exotic and invasive species richness was greatest in historically cleared sites. Non-metric multi-dimensional scaling (NMS) ordination was used to identify associations between community assemblage, land use history, and dispersal mechanism. The two axes of the NMS ordination explained 79.2% of the variation in the data, and indicated that woodlots completely cleared in the past were associated with wind dispersed species indicative of disturbed habitats. In contrast, historically uncleared sites contained short-distance dispersed species indicative of rich woods. Although no effects of recent disturbance were detected, the long lived impacts of past land use and the increase of exotic and invasive species in historically cleared indicate that undisturbed woodlots should be considered of highest conservation importance.

The purpose of this study was to determine the effects of contrasting agricultural practices in organic and conventional farming (local factors), and to evaluate the influence of surrounding landscape features (regional factors) on plant assemblages, taking into account habitat structure. Plants were inventoried in crop fields and woody hedgerows (boundary and centre) of 16 conventional and 14 organic sites. Habitat structure, agricultural practices and landscape characteristics were quantified for each habitat. Hedgerow boundaries contained a higher number of plant species than adjacent habitats although many of them were exotics. However, exotics comprised a decreasing proportion of species richness from field to hedgerow centre. Many of the exotic species were shared between crop fields and adjacent boundaries. There was a clear difference in species richness and composition between the organic and conventional study sites. Fields and woody hedgerows situated in organic sites consistently harboured more native and exotic plant species than those in conventional systems. Numerous species were only found in organic hedgerows and included several long-lived herbaceous forest species. At the larger scale level, old-fields (areas with sparse shrubs and trees re-colonizing cleared land) were the only habitats that significantly influenced the species composition of hedgerows, particularly exotic species. Conversely, farm type was a significant predictor of native species richness.